408 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
called the squamosal. In Sphenodon, by the time the adult con¬ 
dition is reached the squamosal has extended a dorsal process to 
the parietal (fig. P) thus resembling to a certain extent the con¬ 
dition found in Amphiuma (pi. 40, fig. 4) so that this element in its 
relations exhibits characters of both squamosal and supratemporal, 
relations which led Baur to maintain that both elements were pres¬ 
ent in the single bone. The development, however, shows that this 
supposition is untenable (vide Howes and Swinnerton, :01). 
The reconstruction of Palaeohatteria by Woodward (’98, p. 185) 
shows no such process to the squamosal but the sides of the parietal 
(represented by Credner, ’81-’ 89, by dotted lines) are produced to meet 
Fig. O. — Lateral aspect of developing skull of Sphenodon (Hatteria), but a 
somewhat older stage than that represented in Fig. N, after Schauinsland. 
Pf., postfrontal; Po., postorbital; Qj., quadratojugal; Qu., quadrate; 
Sq., squamosal. 
the squamosal. Apparently the same is true for Stenometopon. 
The differences between the living and the fossil genera are that in 
Sphenodon with the loss of the supratemporal, the squamosal has 
been produced to meet the parietal while in the other genera men¬ 
tioned, an outgrowth from the parietal extends to the squamosal. 
The squamosal in Sphenodon.is the mastoid of Gunther, the supra¬ 
temporal of Siebenrock (’93), the paraquadrate of Gaupp, and the 
squamosal of most other authors. 
The lower arcade in Sphenodon is formed of jugal and squamosal, 
